Navigation system

ABSTRACT

A navigation system includes a sensing device and an environment map creator. The sensing device generates environment information which indicates a shape of a shore arrival location. The environment map creator creates an environment map which indicates the shape of the shore arrival location based on the environment information.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a navigation system.

2. Description of the Related Art

Japanese Patent Laid-open No. S58-9014 discloses a method for setting a course between a departure place and a destination on the basis of the longitude and the latitude of the destination, and automatically operating a large boat according to the set course.

However, in the method disclosed in Japanese Patent Laid-open No. S58-9014, although the large boat arrives at the destination due to the automatic boat operation, the shape of the shore arrival location (pier, quay, etc.) at the destination is unknown. As a result, there is a need to visually confirm the shore arrival location while manually operating the large boat when approaching the destination.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide navigation systems that are each able to guide a boat to a shore arrival location.

A navigation system according to a preferred embodiment of the present invention includes a sensing device and an environment map creator. The sensing device generates environment information which indicates the shape of a shore arrival location. The environment map creator creates an environment map which indicates the shape of the shore arrival location based on the environment information.

In a preferred embodiment of the present invention, a navigation system is provided that is able to guide a boat to a shore arrival location.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a boat according to a preferred embodiment of the present invention.

FIG. 2 is a side view of the boat.

FIG. 3 is a side cross-sectional view illustrating a configuration of a first propulsion device of the boat.

FIG. 4 is a schematic view illustrating a boat operating mechanism and a control system of the boat.

FIG. 5 is a flow chart illustrating automatic shore arrival control processing.

FIG. 6 is a flow chart illustrating automatic shore arrival control processing.

FIG. 7 is a flow chart illustrating automatic shore arrival control processing.

FIG. 8 is a flow chart illustrating automatic shore arrival control processing.

FIG. 9 is a view illustrating an operation screen.

FIG. 10 is a view illustrating an input and correction method of a target position for shore arrival.

FIG. 11 is a view illustrating an input and correction method of a target position for shore arrival.

FIG. 12 is a view illustrating an automatic setting method of the target position for shore arrival.

FIG. 13 is a view illustrating an example of an environment map.

FIG. 14 is a view illustrating a determination method for an offset amount.

FIG. 15 is a view illustrating a determination method for a target navigation route.

FIG. 16 is a view illustrating a control block for determining a target velocity and angular speed.

FIG. 17 is a view illustrating a control block for determining a target propulsion force and steering angle.

FIG. 18 is a flow chart illustrating transmission processing for transmitting environment information to a server.

FIG. 19 is a flow chart illustrating creation processing for creating an environment map in the server.

FIG. 20 is a schematic view of an environment map which indicates the shape of a shore arrival location.

FIG. 21 is a schematic view of an object environment map which indicates the shape in the vicinity of the shore arrival location.

FIG. 22 is a schematic view of an environment map which indicates the shapes of boats moored at the shore arrival location.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is an explanation of boats according to preferred embodiments of the present invention with reference to the drawings. FIG. 1 is a plan view of a boat 1. In FIG. 1, a portion of the configuration inside the boat 1 is depicted. FIG. 2 is a side view of the boat 1. In the present preferred embodiment, the boat 1 is a jet propulsion boat, for example, and is a type of boat called a jet boat or a sports boat.

The boat 1 includes a boat body 2, engines 3L and 3R, and propulsion devices 4L and 4R. The boat body 2 includes a deck 11 and a hull 12. The hull 12 is disposed below the deck 11. An operator's seat 13 and a passenger seat 17 are disposed on the deck 11.

The boat 1 includes two engines 3L and 3R and two propulsion devices 4L and 4R, for example. Specifically, the boat 1 includes a first engine 3L and a second engine 3R. The boat 1 includes a first propulsion device 4L and a second propulsion device 4R. However, the number of engines is not limited to two and there may be one engine or three or more engines. The number of propulsion devices is not limited to two and there may be one propulsion device or three or more propulsion devices.

The first engine 3L and the second engine 3R are contained in the boat body 2. The output shaft of the first engine 3L is connected to the first propulsion device 4L. The output shaft of the second engine 3R is connected to the second propulsion device 4R. The first propulsion device 4L is driven by the first engine 3L to produce a propulsion force to move the boat body 2. The second propulsion device 4R is driven by the second engine 3R to produce a propulsion force to move the boat body 2. The first propulsion device 4L and the second propulsion device 4R are disposed side by side to the right and left of each other.

The first propulsion device 4L is a propulsion device that sucks in and jets water around the boat body 2. FIG. 3 is a side view illustrating a configuration of the first propulsion device 4L. A portion of the first propulsion device 4L is illustrated as a cross-section in FIG. 3.

As illustrated in FIG. 3, the first propulsion device 4L includes a first impeller shaft 21L, a first impeller 22L, a first impeller housing 23L, a first nozzle 24L, a first deflector 25L, and a first reverse bucket 26L. The first impeller shaft 21L extends in the front-back direction. The front portion of the first impeller shaft 21L is connected to the output shaft of the engine 3L via a coupling 28L. The rear portion of the first impeller shaft 21L is disposed inside the first impeller housing 23L. The first impeller housing 23L is disposed behind a water suction portion 27L. The first nozzle 24L is disposed behind the first impeller housing 23L.

The first impeller 22L is attached to the rear portion of the first impeller shaft 21L. The first impeller 22L is disposed inside the first impeller housing 23L. The first impeller 22L rotates with the first impeller shaft 21L and sucks in water from the water suction portion 27L. The first impeller 22L jets the sucked in water from the first nozzle 24L to the rear.

The first deflector 25L is disposed behind the first nozzle 24L. The first reverse bucket 26L is disposed behind the first deflector 25L. The first deflector 25L switches the jetting direction of the water from the first nozzle 24L to the left and right directions. That is, by changing the bearing of the first deflector 25L in the left and right directions, the traveling direction of the boat 1 is changed to the left or right.

The first reverse bucket 26L is able to switch between a forward travel position and a reverse travel position. While the first reverse bucket 26L is in the forward travel position, water from the first nozzle 24L and the first deflector 25L is jetted toward the rear. As a result, the boat 1 travels forward. While the first reverse bucket 26L is in the reverse travel position, the jetting direction of the water from the first nozzle 24L and the first deflector 25L is changed to the front. As a result, the boat 1 travels in reverse.

Although omitted in the drawings, the second propulsion device 4R includes a second impeller shaft, a second impeller, a second impeller housing, a second nozzle, a second deflector, and a second reverse bucket. The second impeller shaft, the second impeller, the second impeller housing, the second nozzle, the second deflector, and the second reverse bucket are respectively configured in the same way as the first impeller shaft 21L, the first impeller 22L, the first impeller housing 23L, the first nozzle 24L, the first deflector 25L, and the first reverse bucket 26L, and explanations thereof are omitted.

Next, the boat operating mechanism and the control system of the boat 1 will be explained. FIG. 4 is a schematic view illustrating the boat operating mechanism and the control system of the boat 1. As illustrated in FIG. 4, the boat 1 includes a controller 41. The controller 41 includes a computation device such as a CPU and a storage device such as a RAM or a ROM, and is configured or programmed so as to control the boat 1.

The boat 1 includes a first engine control unit (ECU) 31L, a first steering actuator 32L, a first steering control unit (CU) 33, a first shift actuator 34L, and a first shift control unit (CU) 35L. The above elements control the first propulsion device 4L. Each of the first ECU 31L, the first steering CU 33L, and the first shift CU 35L include a computation device such as a CPU and a storage device such as a RAM or a ROM, and are configured or programmed so as to control the device to which they are connected.

The first ECU 31L is communicatively connected to the first engine 3L. The first ECU 31L outputs an instruction signal to the first engine 3L.

The first steering actuator 32L is connected to the first deflector 25L of the first propulsion device 4L. The first steering actuator 32L changes the steering angle of the first deflector 25L. The first steering actuator 32L is, for example, an electric motor. The first steering CU 33L is communicatively connected to the first steering actuator 32L. The first steering CU 33L outputs an instruction signal to the first steering actuator 32L.

The first shift actuator 34L is connected to the first reverse bucket 26L of the first propulsion device 4L. The first shift actuator 34L switches the position of the first reverse bucket 26L between the forward travel position and the reverse travel position. The first shift actuator 34L is, for example, an electric motor. The first shift CU 35L is communicatively connected to the first shift actuator 34L. The first shift CU 35L outputs an instruction signal to the first shift actuator 34L.

The boat 1 includes a second ECU 31R, a second steering actuator 32R, a second steering CU 33R, a second shift actuator 34R, and a second shift CU 35R. The above elements control the second propulsion device 4R and are configured in the same way as the above-described first ECU 31L, the first steering actuator 32L, the first steering CU 33L, the first shift actuator 34L, and the first shift CU 35L, respectively.

The boat 1 includes a steering device 14, a joystick 42, a remote control unit 15, a display 43, an input 44, a positional sensor 45, and a sensing device 46. The steering device 14, the display 43, the input 44, the positional sensor 45, and the sensing device 46 are communicatively connected to the controller 41, the first and second ECUs 31L and 31R, the first and second steering CUs 33L and 33R, and the first and second shift CUs 35L and 35R. For example, the above devices are connected to each other over a control area network (CAN) or a CAN with a flexible data rate (CAN-FD).

Due to the above devices being connected to each other, the transmission of information between each of the devices is possible at the same time. Consequently, adjustment control of the steering, shifting, and throttling are performed easily. In addition, the connections of the above devices define a duplex system. As a result, stable communication is maintained.

The remote control unit 15 has an analog connection with the controller 41. However, the remote control unit 15 may be connected over the CAN network or the like in the same way as the other devices.

The steering device 14 is disposed at the operator's seat 13. The steering device 14 includes, for example, a steering wheel. The steering device 14 is operated to steer the boat body 2. The steering device 14 outputs operation signals. The first steering CU 33L and the second steering CU 33R control the first and second steering actuators 32L and 32R in accordance with the operation of the steering device 14. Consequently, the traveling direction of the boat 1 is changed to the left or right.

The remote control unit 15 is disposed at the operator's seat 13. The remote control unit 15 is operated to adjust the output of the engines 3L and 3R, and to switch between forward and reverse travel. The remote control unit 15 includes a first throttle operating member 15L and a second throttle operating member 15R. The first throttle operating member 15L and the second throttle operating member 15R are, for example, lever-shaped members.

The remote control unit 15 outputs signals to indicate the operation amount and operating direction of the first and second throttle operating members 15L and 15R. The first ECU 31L controls the rotation speed of the first engine 3L in response to the operation amount of the first throttle operating member 15L. The second ECU 31R controls the rotation speed of the second engine 3R in response to the operation amount of the second throttle operating member 15R.

The first shift CU 35L controls the first shift actuator 34L in response to the operating direction of the first throttle operating member 15L. The second shift CU 35R controls the second shift actuator 34R in response to the operating direction of the second throttle operating member 15R. As a result, the travel direction of the boat 1 is switched between forward and reverse travel.

The joystick 42 is disposed at the operator's seat 13. The joystick 42 is operated to cause the boat body 2 to move forward and reverse and left and right. In addition, the joystick 42 is operated to change the bearing of the boat body 2. The operation signals from the joystick 42 are inputted to the controller 41. The controller 41 controls the first and second engines 3L and 3R, the first and second steering actuators 32L and 32R, and the first and second shift actuators 34L and 34R. As a result, the boat 1 moves forward and reverse and to the left and right. Alternatively, the boat 1 is turned to change the bearing.

The display 43 and the input 44 are disposed at the operator's seat 13. The display 43 displays information pertaining to the boat 1. The display 43 receives display information from the controller 41. The display 43 displays information in response to the display signals from the controller 41.

The input 44 accepts inputs pertaining to the boat 1. The input 44 outputs input signals indicating the inputted information. The input 44 may be integral with the display 43 and include a touch panel. Alternatively, the input 44 may be separate from the display 43.

The positional sensor 45 detects the current position and the current bearing of the boat body 2 and outputs position information indicating the current position and the current bearing. The positional sensor 45 is, for example, an inertial navigation device and includes a global navigation satellite system (GNSS) device 47 and an inertial measurement unit (IMU) 48. The GNSS device 47 detects the current position and the boat speed of the boat body 2. The IMU 48 detects the angular speed and the acceleration of the boat body 2. In addition, the current bearing of the boat body 2 is detected by the GNSS device 47 and the IMU 48. The current bearing may be detected by a plurality of GNSS devices, a magnetic bearing sensor, or an electronic compass.

The sensing device 46 includes one type of sensor or a plurality of types of sensors among a radar, a laser, a camera or an ultrasonic sensor. The sensing device 46 may include a plurality of radars, a plurality of lasers, a plurality of cameras, or a plurality of ultrasonic sensors. The radar includes, for example, a millimeter wave radar, a microwave radar, or another radar of a different wavelength. The sensing device 46 generates and outputs environment information.

The environment information indicates the shape of a shore arrival location, the positional relationship between the shore arrival location and the boat body 2, and objects (such as another boat, a structure, an obstruction, etc.) in the vicinity of the shore arrival location. The environment information may indicate the shore arrival location or structures or obstructions surrounding the boat body 2. The environment information is indicated, for example, by coordinates of point groups indicating the position of an object detected by the sensing device 46. Alternatively, the environment information may be the shape and position of an object captured by image recognition.

As illustrated in FIG. 4, the sensing device 46 may be connected to the CAN or the CAN-FD through a programmable logic device (PLD) such as a field-programmable gate array (FPGA) 49 or the like. Alternatively, the sensing device 46 may be connected to the CAN or the CAN-FD through a digital signal processor (DSP).

A transmitter/receiver 50 is able to transmit and receive information with a server 51 over a boat-land intercommunication line. A mobile telephone line, a wireless local area network (LAN) line that conforms to the Wi-Fi (trademark) standard, a personal handy-phone system (PHS) line, or a satellite communication line such as the International Marine Satellite Organization (INMARSAT), or the like may be used as the boat-land intercommunication line.

The transmitter/receiver 50 obtains, from the controller 41, the environment information outputted by the sensing device 46 and position information of the host boat detected by the positional sensor 45, after an automatic shore arrival control described below has ended. The transmitter/receiver 50 transmits the obtained environment information and the position information to the server 51.

The server 51 is, for example, a virtual server (cloud server) or a physical server. In the present preferred embodiment, the server 51 is an example of an “environment map creator.” The server 51 gathers environment information and position information not only from the boat 1, but also from boats other than the boat 1. The server 51 creates the environment map which indicates the shape of the shore arrival location based on the environment information gathered from each boat. In addition, the server 51 indicates the shapes of obstructions in the vicinity of the shore arrival location and the shapes of structures in the vicinity of the shore arrival location on the environment map based on the gathered environment information. Furthermore, the server 51 indicates, on the environment map, the positions and shapes of other boats moored at the shore arrival location based on the position information gathered from other boats. The server 51 updates the shapes of boats, obstructions, and structures on the environment map every time new environment information or position information is obtained. As a result, the environment in the vicinity of the shore arrival location is updated on the environment map.

The transmitter/receiver 50 transmits an environment map transmission request to the server 51. The transmitter/receiver 50 receives the environment map from the server 51 when the server 51 includes the environment map. The transmitter/receiver 50 transmits the environment map received from the server 51 to the controller 41. The environment map obtained from the server 51 is used in the automatic shore arrival control described below.

In the present preferred embodiment, the controller 41, the positional sensor 45, the sensing device 46, the transmitter/receiver 50, and the server 51 define a “navigation system” that guides the boat 1 to the shore arrival location.

The boat 1 includes an automatic shore arrival function. The automatic shore arrival function automatically enables the boat body 2 to arrive at a shore arrival location such as a pier without operations by the operator. Hereinbelow, the automatic shore arrival control executed by the automatic shore arrival function will be explained in detail. FIGS. 5 to 8 are flow charts of a process of the automatic shore arrival control executed by the controller 41.

As illustrated in FIG. 5, the controller 41 obtains current position information from the positional sensor 45 in step S101. The controller 41 obtains the current position and the current bearing of the boat body 2 in real time from the position information.

In step S102, the controller 41 determines whether the environment map has been obtained from the server 51. When the environment map is obtained from the server 51, the processing advances to step S106. When the environment map is not obtained from the server 51, the processing advances to step S103.

In step S103, the controller 41 evaluates whether the sensing device 46 has captured a sensing object. When an object is captured by the sensing device 46, the processing advances to step S104.

In step S104, the controller 41 obtains, from the sensing device 46, the environment information which indicates the shape of the shore arrival location, the positional relationship between the shore arrival location and the boat body 2, and an object (another boat, a structure, an obstruction, or the like) in the vicinity of the shore arrival location.

In step S105, the controller 41 or the FPGA 49 recognizes a shore arrival location, another boat, an obstruction, or a surrounding structure based on the environment information. The shore arrival location is, for example, a pier. The controller 41 or the FPGA 49 recognizes another boat or an obstruction based on the shape of the object detected by the sensing device 46. For example, the controller 41 or the FPGA 49 recognizes the shore arrival location and the surrounding structure based on the height and length of the object detected by the sensing device 46.

In step S106, the controller 41 displays an environment map indicating the surrounding environment on the display 43. FIG. 9 is a view illustrating an operation screen 61 of the automatic shore arrival function. As illustrated in FIG. 9, the operation screen 61 is displayed by a GUI on the display 43. The operation screen 61 includes an environment map 62 and a plurality of operating keys. By pressing the plurality of operating keys, the inputs of the various operations of the automatic shore arrival function are accepted by the input 44.

The shapes of the shore arrival location, the obstructions, and the surrounding structures are displayed on the environment map 62. While not illustrated in FIG. 9, other boats recognized by the controller 41 are also displayed on the environment map 62. The controller 41 displays the current position and the current bearing of the boat body 2 obtained from the position information on the environment map 62 with an icon 71 of the boat body 2. The controller 41 displays the current position and the current bearing of the boat body 2 obtained from the position information on the environment map 62 with an icon 71 of the boat body 2.

The environment map 62 is updated in real time due to the repeated detection of the position information by the positional sensor 45 and the repeated detection of the environment information by the sensing device 46. The plurality of operating keys include a scale changing key 63. By operating the scale changing key 63, the displayed scale of the environment map 62 is enlarged or reduced.

FIG. 6 is a flow chart illustrating processing to set a target position of the shore arrival. As illustrated in step S201 in FIG. 6, the controller 41 determines a possible shore arrival space. The controller 41 determines the possible shore arrival space based on the environment information. As illustrated in FIG. 10, the controller 41 determines a position along the object recognized as the shore arrival location, as a possible shore arrival space SP1. For example, the controller 41 detects the disposition of the pier from the environment information and determines a predetermined range along the pier as the possible shore arrival space SP1.

Moreover, the controller 41 detects the dispositions of the shore arrival location and of another boat docked at the shore arrival location from the environment information, and determines the possible shore arrival space SP1 from the dispositions of the shore arrival location and the other boat. As illustrated in FIG. 10, when two other boats 201 and 202 are docked with an interval therebetween, the controller 41 calculates a distance dl between the two other boats 201 and 202. The controller 41 then determines that the space between the two other boats 201 and 202 is able to serve as the possible shore arrival space SP1 when the distance dl between the two other boats 201 and 202 is greater than a threshold which indicates a space in which docking by the host boat is possible.

In step S202, the controller 41 displays the possible shore arrival location on the environment map 62. The possible shore arrival location may be the above-described possible shore arrival space SP1. Alternatively, the possible shore arrival location may be a specified position inside the possible shore arrival space SP1. The environment map 62 on which the possible shore arrival location is displayed may be a bird's-eye view as illustrated in FIG. 9. Alternatively, an image captured by a camera may be displayed as the environment map 62. In this case, the possible shore arrival location may be displayed on the image captured by the camera.

In step S203, the controller 41 evaluates whether there is an input of the target position for the shore arrival. Here, the input of the target position on the environment map 62 is accepted by the input 44. The operator touches the possible shore arrival location on the environment map 62, such that the touched position is inputted as the target position. The input 44 outputs target position information which indicates the target position to the controller 41.

In step S204, the controller 41 evaluates whether the inputted target position is within a suitable range SP2. When the inputted target position is within the suitable range SP2, the processing advances to step S205.

In step S205, the controller 41 corrects the target position. The controller 41 corrects the target position based on the possible shore arrival space SP1. For example, as illustrated in FIG. 10, when an inputted target position IP1 is outside of the possible shore arrival space SP1, the controller 41 corrects a target position Tp so that the target position is within the possible shore arrival space SP1. When an inputted target position IP2 is inside the possible shore arrival space SP1, the controller 41 corrects the target position Tp so that the target position becomes the center position of the possible shore arrival space SP1.

As illustrated in FIG. 9, the operation screen 61 includes a target position setting key 64. When the target position setting key 64 is pressed, the operator is able to manually input any position without being limited to the space SP1. Therefore, the touched position is received as the target position by the input 44. In this case, when the position spaced away from the shore arrival location in a direction perpendicular or substantially perpendicular to the direction along the shore arrival location is inputted as the target position, the controller 41 may correct the target position to a position along the shore arrival location. At this time, as illustrated in FIG. 11, the target position Tp is preferably corrected to a position closest to the inputted target position IP3 within the position along the shore arrival location.

When there is no input of the target position in step S203, the processing advances to step S206. For example, when a touch of the environment map 62 has not been detected for a predetermined time period, the processing advances to step S206.

In step S206, the controller 41 automatically sets the target position. Here, as illustrated in FIG. 12, the controller 41 sets the closest position in the current bow direction among the positions along the shore arrival location, as the target position.

In step S207, the controller 41 displays the target position and the target bearing with an icon 71′ on the environment map 62. Here, as illustrated in FIG. 9, the controller 41 sets the target position corrected in step S205 or the target position automatically set in step S206 as the target position, and displays the icon 71′ which indicates the host boat in the position on the environment map 62. The icon 71′ is displayed in the target bearing determined by the controller 41 in the initial state. The controller 41 determines the target bearing of the boat body 2 based on the shape of the shore arrival location, the current bearing, the distance to the target position, or the like. For example, when the shore arrival location is a pier, the controller 41 determines a direction along the edge of the shore arrival location as the target bearing. Alternatively, the controller 41 may determine a direction that defines a predetermined angle with the direction along the edge of the shore arrival location, as the target bearing. Moreover, the controller 41 may change the target bearing in response to the current bearing or the distance to the target position.

As illustrated in FIG. 9, the operation screen 61 includes a first bearing changing key 65 and a second bearing changing key 66. The target bearing is changed by a predetermined angle (for example, about 90° at a time) each time the first bearing changing key 65 is pressed. However, the unit angle for the changing is not limited to 90° and may be smaller than 90° or greater than 90°. The second bearing changing key 66 is rotatably provided on the operation screen 61. The target bearing is changed in response to the rotation of the second bearing changing key 66. The bearing of the icon 71′ of the host boat on the environment screen is changed in response to the change of the target bearing.

When the inputted target position is not within a suitable range SP2 in step S204, the target position is not corrected and the inputted target position is set as the target position. For example, as illustrated in FIG. 10, the suitable range SP2 is a range that includes the possible shore arrival space SP1. When the inputted target position IP4 is outside of the suitable range SP2, the target position is not corrected. Therefore, when the inputted target position IP4 is spaced away from the possible shore arrival space SP1 by a predetermined distance or more, the inputted target position is not corrected and is set as the target position. The size of the suitable range SP2 is set to a value that is able to be determined when a position spaced away from the possible shore arrival space SP1 is intentionally touched without the target position input being shifted.

As illustrated in FIG. 9, the operation screen 61 includes an automatic shore arrival mode start button 67 and an automatic shore arrival mode stop button 68. As indicated above, after the target position has been set, the automatic shore arrival control is started when the operator presses the automatic shore arrival mode start button 67. When the automatic shore arrival control is started, the controller 41 generates instruction signals to control the propulsion devices 4L and 4R so that the boat body 2 arrives at the target position. Hereinbelow, the processing to start and end the automatic shore arrival control will be explained.

As illustrated in step S301 in FIG. 7, the controller 41 evaluates whether the automatic shore arrival control has started. When the automatic shore arrival mode start button 67 is pressed, the processing advances to step S302. In step S302, the controller 41 evaluates whether the boat 1 has reached a second target position.

As illustrated in FIG. 13, with the target position and the target bearing determined in above-described steps S201 to S207 being established as the first target position TP1, the second target position TP2 is a position spaced away from the first target position TP1 by a predetermined offset amount on the current position side of the boat 1. In the automatic shore arrival control, the controller 41 firstly controls the propulsion devices 4L and 4R so that the boat 1 reaches the second target position TP2, and then controls the propulsion devices 4L and 4R so that the boat 1 reaches the first target position TP1. The second target position TP2 is explained below.

When the boat 1 has not reached the second target position TP2 in step S302, the processing advances to step S303. In step S303, the controller 41 evaluates whether a position error and a bearing error are equal to or less than first thresholds. The position error is the distance between the current position of the boat body 2 and the second target position TP2. The bearing error is the difference between the current bearing of the boat body 2 and the target bearing. When the distance between the current position of the boat body 2 and the second target position TP2 is equal to or less than a first position threshold, and the difference between the current bearing of the boat body 2 and the target bearing is less than a first bearing threshold, the controller 41 determines that the position error and the bearing error are equal to or less than the first thresholds. When the position error and the bearing error are not equal to or less than the first thresholds, the processing advances to step S304.

In step S304, the controller 41 determines the second target position TP2. As illustrated in FIG. 14, the controller 41 calculates the bearing difference between the current bearing and the target bearing, and determines an offset amount L of the first target position TP1 in response to the bearing difference. The controller 41 determines a position spaced away by the offset amount from the first target position TP1 on the current position side as the second target position TP2. That is, the controller 41 determines a position spaced away by the offset amount L from the first target position TP1 in the direction perpendicular or substantially perpendicular to the edge of the shore arrival location, as the second target position TP2. Specifically, when the shore arrival location is a pier, the controller 41 uses the following equation 1 to determine the offset amount. L=a×|Heading_err/90|+b+W  Equation 1

L is the offset amount. a is a predetermined coefficient and is determined based on the distance between the center of gravity and the bow of the boat body 2. The Heading_err is the bearing difference between the current bearing and the first target bearing as illustrated in FIG. 14. However when the Heading_err is equal to or greater than 90°, the Heading_err is set to 90°. b is a margin corresponding to the boat body 2 with respect to the target bearing and the direction along the edge of the shore arrival location. W is the width of another boat.

That is, the controller 41 calculates the bearing difference between the current bearing and the target bearing and calculates the margin that corresponds to the boat body 2. The controller 41 determines the offset amount L of the first target position TP1 in response to the bearing difference and the margin that corresponds to the boat body 2.

Therefore, the controller 41 increases the offset amount in response to the size of the bearing difference Heading_err. The controller 41 determines the offset amount based on the distance between the center of gravity and the bow of the boat body 2. The controller 41 determines the offset amount so as to be greater than the width W of another boat docked at the shore arrival location. The offset amount is calculated and updated in real time.

As illustrated in FIG. 13, when an obstruction X1 is present between the first target position TP1 and the current position, the controller 41 determines the second target position TP2 so as to avoid the obstruction. Specifically, as illustrated in FIG. 15, a grid is provided on the environment map 62. The controller 41 determines the second target position TP2 by excluding the grid within a predetermined range from the obstruction X1.

In addition, the controller 41 determines a target navigation route Phi to the second target position TP2. The controller 41 establishes the shortest route to the second target position TP2 within the route that passes through the set grid, as the target navigation route Phi. At this time, when an obstruction is present, the controller 41 determines the target navigation route Phi by excluding the grid within the predetermined range from the object recognized as the obstruction. The determined target navigation route Phi is displayed on the environment map 62. The controller 41 calculates and updates the target navigation route Phi in real time.

The disposition of the grid is set so that a predetermined number of grids are disposed between the current position of the boat body 2 and the target position. Therefore, when the distance between the boat body 2 and the target position is changed, the disposition of the grid is changed.

As shown in step S305 in FIG. 7, the controller 41 changes the target position from the first target position TP1 to the second target position TP2.

When the position error and the bearing error are equal to or less than the first thresholds in step S303, the processing advances to step S306. That is, the processing advances to step S306 when the current position is near the second target position TP2 and the current bearing is near the target bearing without the boat 1 having completely reached the second target position TP2.

In step S306, the controller 41 determines a target speed and a target angular speed from the target position and the target bearing.

When the boat 1 has not yet entered a predetermined range from the second target position TP2 (“No” in S303), the controller 41 sets the second target position TP2 as the target position and determines the target speed and the target angular speed. When the boat 1 has entered the predetermined range from the second target position TP2 (“Yes” in S302 or S303), the controller 41 sets the first target position TP1 as the target position and determines the target speed and angular speed.

As illustrated in FIG. 16, the controller 41 calculates a relative error Pb_err from the target position and the current position and from the target bearing and the current bearing, and determines a target speed and angular speed Vc based on the relative error Pb_err. The controller 41 reduces the target speed and angular speed Vc in response to a reduction in the relative error Pb_err. That is, the controller 41 reduces the target speed as the current position of the boat body 2 approaches the target position. The controller 41 reduces the target angular speed as the current bearing of the boat body 2 approaches the target bearing. When the distance between the current position of the boat body 2 and the target position enters a predetermined range that includes zero, the controller 41 sets the target speed to zero. Moreover, when the difference between the current position of the boat body 2 and the target position enters the predetermined range that includes zero, the controller 41 sets the target angular speed to zero.

The relative error Pb_err includes a first position error Pb_err_x, a second position error Pb_err_y, and a bearing error Pb_err_θ. The first position error Pb_err_x is the distance between the target position and the current position in the front-back direction of the boat body 2. The second position error Pb_err_y is the distance between the target position and the current position in the left-right direction of the boat body 2. The bearing error Pb_err_θ is the difference between the target bearing and the current bearing.

The target speed and angular speed Vc includes a first target speed Vc_x, a second target speed Vc_y, and a target angular speed ωc. The first target speed Vc_x is the target speed in the front-back direction of the boat body 2. The second target speed Vc_y is the target speed in the left-right direction of the boat body 2. The target angular speed ωc is the target angular speed of the boat body 2.

The controller 41 stores first target speed information Ivcx, second target speed information Ivcy, and target angular speed information Iωc. The first target speed information Ivcx defines the relationship between the first position error Pb_err_x and the first target speed Vc_x. The second target speed information Ivcy defines the relationship between the second position error Pb_err_y and the second target speed Vc_y. The target angular speed information Iωc defines the relationship between the bearing error Pb_err_θ and the target angular speed ωc. The above sets of information Ivcx to Iωc may be represented, for example, by maps, tables, numerical calculations, or equations, etc.

The controller 41 determines the first target speed Vc_x from the first position error Pb_err_x based on the first target speed information Ivcx. The controller 41 determines the second target speed Vc_y from the second position error Pb_err_y based on the second target speed information Ivcy. The controller 41 determines the target angular speed ωc based on the target angular speed information Iωc.

Alternatively, the target speed and angular speed Vc may be determined with the following equation 2. Any of the first position error Pb_err_x, the second position error Pb_err_y, the bearing error Pb_err_θ, the actual speed Vx in the front-back direction of the boat body 2, the actual speed Vy in the left-right direction, and the actual angular speed w may be used as inputs.

$\begin{matrix} {{Vc} = {\begin{pmatrix} {Vc\_ x} \\ {Vc\_ y} \\ {\omega\; c} \end{pmatrix} = {f\left( {{{Pb\_ err}{\_ x}},{{Pb\_ err}{\_ y}},{{Pb\_ err}{\_\theta}},{Vx},{Vy},\omega} \right)}}} & {{Equation}\mspace{14mu} 2} \end{matrix}$

As shown in step S401 in FIG. 8, the controller 41 evaluates whether the distance from the current position to the target position is equal to or less than a predetermined threshold Dt1. When the distance to the target position is not equal to or less than the predetermined threshold Dt1, the processing advances to step S402. In step S402, the boat body 2 is controlled using an approach control. In the approach control, the controller 41 determines a target propulsion force and a target steering angle of the propulsion devices 4L and 4R based on the first target speed Vc_x and the target angular speed ωc.

When the distance from the current position to the target position is equal to or less than the predetermined threshold Dt1 in step S401, the processing advances to step S403. In step S403, the boat body 2 is controlled using an adjust control. In the adjust control, the target propulsion force and the target steering angle of the propulsion devices 4L and 4R are determined based on the first target speed Vc_x, the second target speed Vc_y, and the target angular speed ωc.

In this way, when the distance to the target position is greater than the predetermined threshold Dt1, the target position and the target bearing are reached promptly under the approach control. When the distance to the target position is equal to or less than the predetermined threshold Dt1, the boat body 2 is able to be brought to the target position with high accuracy under the adjust control.

In step S402 and step S403, the controller 41 calculates a force caused by an outside disturbance and determines the target propulsion force and the target steering angle of the propulsion devices 4L and 4R in consideration of the force of the outside disturbance. The outside disturbance includes, for example, the tidal current or the wind. Fluctuations in the resistance to the boat body caused by weight fluctuations and the like are included in the calculated results. Specifically, the controller 41 determines the target propulsion force and the target steering angle based on the force of the outside disturbance, the target speed, and the target angular speed. FIG. 17 is a control block diagram for determining the target propulsion force and the target steering angle.

As illustrated in FIG. 17, the controller 41 includes an outside disturbance observer 411 and a target propulsion force and steering angle computing unit 412. The outside disturbance observer 411 calculates an outside disturbance force w based on the actual speed and angular speed V of the boat body 2, the actual engine rotation speed n1 of the first engine 3L, the actual engine rotation speed n2 of the second engine 3R, the actual steering angle δ1 of the first propulsion device 4L, and the actual steering angle δ2 of the second propulsion device 4R. The actual speed and angular speed V of the boat body 2 includes the actual speed Vx in the front-back direction of the boat body 2, the actual speed Vy in the left-right direction, and the actual angular speed w.

The target propulsion force and steering angle computing unit 412 calculates a target propulsion force based on the target speed and angular speed Vc, the actual speed and angular speed V of the boat body 2, and the outside disturbance force w. The controller 41 estimates the outside disturbance force w using the following equation 3. {dot over (V)}=f _(model)(Vx,Vy,ω,n1,n2,δ1,δ2) w={dot over (V)}−{dot over ({circumflex over (V)})}  Equation 3

f_(model) is a motion equation of the boat body 2. {dot over (V)} is the time derivative of V. {dot over ({circumflex over (V)})} is an estimation using the motion equation of the boat body 2.

The controller 41 uses the motion equation represented in the following equation 4 to calculate a target propulsion force based on, for example, the Lyapunov theory of stability. {dot over (V)}=f _(model)(Vx,Vy,ω,n1,n2,δ1,δ2)+w  Equation 4

The target propulsion force and steering angle computing unit 412 determines a target rotation speed nc1 of the first engine 3L and the target rotation speed nc2 of the second engine 3R from the target propulsion force. The controller 41 generates an instruction signal corresponding to the target rotation speed nc1 of the first engine 3L and outputs the instruction signal to the first ECU 31L. The controller 41 generates an instruction signal corresponding to the target rotation speed nc2 of the second engine 3R and outputs the instruction signal to the second ECU 31R.

Moreover, the target propulsion force and steering angle computing unit 412 determines a target steering angle δc1 of the first propulsion device 4L and a target steering angle δc2 of the second propulsion device 4R based on the target speed and angular speed Vc, the actual speed and angular speed V of the boat body 2, and the outside disturbance force w. The controller 41 generates an instruction signal corresponding to the target steering angle δc1 of the first propulsion device 4L and outputs the instruction signal to the first steering CU 33L. The controller 41 generates an instruction signal corresponding to the target steering angle δc2 of the second propulsion device 4R and outputs the instruction signal to the second steering CU 33R.

As illustrated in step S404 in FIG. 8, the controller 41 evaluates whether the position error and the bearing error are equal to or less than second thresholds. Specifically, when the distance between the current position of the boat body 2 and the target position is equal to or less than a second position threshold, and the difference between the current bearing of the boat body 2 and the target bearing is equal to or less than a second bearing threshold, the controller 41 determines that the position error and the bearing error are equal to or less than the second thresholds. The second position threshold is set to a value less than the above-described offset amount.

When the position error and the bearing error are equal to or less than the second thresholds, the controller 41 ends the automatic shore arrival control. Even when an automatic shore arrival mode stop key 68 in FIG. 9 is pressed, the controller 41 ends the automatic shore arrival control.

Next, transmission processing for transmitting the environment information to the server 51 will be explained with reference to FIG. 18.

In step S501, the controller 41 determines whether the automatic shore arrival control has ended. If the automatic shore arrival control has not ended, the processing in step S501 is repeated. If the automatic shore arrival control has ended, the processing advances to step S502.

In step S502, the controller 41 obtains, from the sensing device 46, the environment information which indicates the shape of the shore arrival location and objects (other boats, structures, obstructions, or the like) in the vicinity of the shore arrival location, and obtains, from the positional sensor 45, the position information which indicates the current position and the current bearing of the host boat.

In step S503, the controller 41 transmits the environment information and the position information to the server 512 via the transmitter/receiver 50.

Next, creation processing for creating the environment map in the server 51 will be explained with reference to FIG. 19.

In step S601, the server 51 obtains environment information and position information from one or more boats including the boat 1. The server 51 may use corrected information of positions to improve the accuracy of the position information.

In step S602, the server 51 creates the environment map which indicates the shape of the shore arrival location based on the environment information gathered from each boat. FIG. 20 is a schematic view of the environment map created based on the respective environment information obtained from boats A and B.

In step S603, the server 51 creates the environment map which indicates the shape of objects (other boats, structures, obstructions, or the like) in the vicinity of the shore arrival location based on the environment information obtained from each boat. FIG. 21 is a schematic view of the environment map in which the shape of an object in the vicinity of the shore arrival location is indicated.

In step S604, the server 51 indicates, on the environment map, the positions and shapes of other boats moored at the shore arrival location based on the position information obtained from each boat. FIG. 22 is a schematic view of the environment map in which the respective positions and shapes of boats A and B are indicated.

In step S605, the server 51 transmits the environment map to each boat when a transmission request to transmit the environment map has been received from each boat. The environment map is able to be used in the above-described shore arrival control or used in manual operation in each boat.

As explained above, in the navigation systems according to preferred embodiments of the present invention, the server 51 creates the environment map which indicates the shape of the shore arrival location based on the environment information generated by the sensing device 46. Therefore, the boat is able to be moored promptly because the boat operator is able to see the environment map and confirm the shape of the shore arrival location (pier, quay, or the like) beforehand.

In addition, the environment information indicates the shapes of objects in the vicinity of the shore arrival location, and the server 51 indicates the shapes of the objects in the vicinity of the shore arrival location on the environment map based on the environment information. Therefore, the mooring of the boat is able to be performed more promptly because other boats, structures, or obstructions or the like are confirmed beforehand when the boat operator is mooring the boat.

In addition, the server 51 indicates the shape of the boat 1 on the environment map based on the position information which indicates the current position and the current bearing of the boat 1. Therefore, the shape of the host boat is able to be indicated on the environment map of the server 51 even when the sensing device 46 is installed on the boat 1.

In addition, the boat 1 uses the environment map obtained from the server 51 in the automatic shore arrival control. Therefore, the automatic shore arrival control is executed promptly because there is no need to detect the environment information with the sensing device 46.

Although preferred embodiments of the present invention have been described so far, the present invention is not limited to the above preferred embodiments and various modifications may be made within the scope of the present invention.

The boat 1 is not limited to a jet propulsion boat and may be another type of boat. For example, the boat 1 may be a boat provided with outboard motors that includes propellers driven by the engines 3L and 3R. That is, the propulsion devices 4L and 4R are not limited to jet propulsion devices and may be another type of propulsion device such as an outboard motor.

The automatic shore arrival control may be executed in a predetermined low-speed region. For example, the automatic shore arrival control may be executed when the boat speed is a predetermined set speed or less.

The correction method for the target position of the shore arrival may be changed. Alternatively, the correction of the target position may be omitted. The method for determining the second target position may be changed. That is, the method for determining the offset amount may be changed. Alternatively, the setting of the second target position may be omitted. The method for estimating the outside disturbance may be changed. Alternatively, the estimation of the outside disturbance may be omitted.

While the sensing device 46 is described as being installed on the boat 1, the sensing device 46 may also be installed in the vicinity of the shore arrival location in a marina. In this case, the environment information which indicates the shape of the shore arrival location, the shapes of all moored boats, the shapes of obstructions, and the shapes of structures, is able to be obtained regularly. As a result, the server 51 is able to reflect the latest entry and departure conditions of boats on the environment map.

The environment map obtained from the server 51 may not be used in the automatic shore arrival control and may be used in normal manual operations of the boat 1.

The variables in the motion equation of the boat body 2 may be changed or other variables may be added. For example, while the state variables of the motion equation of the boat body 2 in the above preferred embodiments are the actual speed Vx in the front-back direction, the actual speed Vy in the left-right direction, and the actual angular speed w of the boat body 2, the variables may be changed or other variables may be added. For example, the state variables may be variables indicating the position and attitude of the boat body 2 such as the position in the front-back direction, the position in the left-right direction, the bearing, the pitch angle, or the roll angle of the boat body 2. While the variables of the motion equation in the above preferred embodiments are the actual engine rotation speeds n1 and n2, and the actual steering angles δ1 and δ2, the variables may be increased or reduced in response to the number of propulsion devices.

According to preferred embodiments of the present invention, a navigation system is provided that is able to guide a boat to a shore arrival location.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A navigation system comprising: a sensor that generates environment information which indicates a shape of a shore arrival location; an environment map creator that creates an environment map which indicates the shape of the shore arrival location based on the environment information; a boat including a boat body and a propulsion device to generate a propulsion force to move the boat body; and a controller configured or programmed to execute an automatic shore arrival control to control the propulsion device so as to cause the boat body to move toward a target position set on the environment map; wherein when a distance from a current position of the boat body to the target position is not equal to or less than a predetermined threshold, the controller executes an approach control that controls the propulsion device based on a first target speed in a front-back direction of the boat body and a target angular speed; and when a distance from the current position to the target position is equal to or less than the predetermined threshold, the controller executes an adjust control that controls the propulsion device based on the first target speed, the target angular speed, and a second target speed in a left-right direction of the boat body.
 2. The navigation system according to claim 1, wherein the environment information indicates the shape of an object in the vicinity of the shore arrival location, and the environment map creator indicates the shape of the object in a vicinity of the shore arrival location on the environment map based on the environment information.
 3. The navigation system according to claim 1, wherein the sensor is installed on the boat.
 4. The navigation system according to claim 1, wherein the sensor is installed at the shore arrival location.
 5. The navigation system according to claim 4, further comprising: a positional sensor that generates position information which indicates a current position and a current bearing of the boat; wherein the environment map creator indicates a shape of the boat on the environment map based on the position information.
 6. A navigation system comprising: a sensor that generates environment information which indicates a shape of a shore arrival location; an environment map creator that creates an environment map which indicates the shape of the shore arrival location based on the environment information; and a boat including a boat body and a propulsion device to generate a propulsion force to move the boat body; and a controller configured or programmed to execute an automatic shore arrival control to control the propulsion device so as to cause the boat body to move toward a target position set on the environment map; wherein the controller determines a target bearing of the boat body based on at least one of the shape of the shore arrival location, a current bearing of the boat body, and a distance from a current position of the boat body to the target position; and the controller changes the target bearing in response to an operation of an operator.
 7. The navigation system according to claim 6, wherein the boat includes a first bearing changer that is able to be pressed by the operator; and the controller is configured or programmed to change the target bearing by a predetermined angle each time the first bearing changer is pressed.
 8. The navigation system according to claim 6, wherein the boat includes a second bearing changer that is able to be rotated by the operator; and the controller changes the target bearing in response to a rotation of the second bearing changer. 